<retrieve>
    <retrieveRequest>
        <apiVersion>31.0</apiVersion>
        <unpackaged>
            <types>
                <members>*</members>
                <name>Profile</name>
            </types>
            <types>
                <members>Task</members>
                <name>CustomObject</name>
            </types>
            <version>31.0</version>
        </unpackaged>
    </retrieveRequest>
</retrieve>

<types>
        <members>Task.Name</members>
        <name>CustomField</name>
    </types>